Improved glucose tolerance and insulin sensitivity after electrical stimulation-assisted cycling in people with spinal cord injury.

DESIGN: Longitudinal training. OBJECTIVES: The purpose was to determine the effect of electrical stimulation (ES)-assisted cycling (30 min/day, 3 days/week for 8 weeks) on glucose tolerance and insulin sensitivity in people with spinal cord injury (SCI). SETTING: The Steadward Centre, Alberta, Canada. METHODS: Seven participants with motor complete SCI (five males and two females aged 30 to 53 years, injured 3-40 years, C5-T10) underwent 2-h oral glucose tolerance tests (OGTT, n=7) and hyperglycaemic clamp tests (n=3) before and after 8 weeks of training with ES-assisted cycling. RESULTS: Results indicated that subjects' glucose level were significantly lower at 2 h OGTT following 8 weeks of training (122.4+/-10 vs 139.9+/-16, P=0.014). Two-hour hyperglycaemic clamps tests showed improvement in all three people for glucose utilisation and in two of three people for insulin sensitivity. CONCLUSIONS: These results suggested that exercise with ES-assisted cycling is beneficial for the prevention and treatment of Type 2 diabetes mellitus in people with SCI. SPONSORSHIP: Supported by Alberta Paraplegic Foundation, Therapeutic Alliance.

Effects of visual impairment on stroke parameters in Paralympic swimmers.

PURPOSE: To examine the relationship between degree of vision and stroking parameters in male and female Paralympic swimmers with visual impairment during the 50- and 100-m freestyle events. METHODS: A video analysis was conducted at the 1996 Paralympic Games in which swimmers competed in three groups based on degree of impairment (S11, S12, and S13; S11 least amount of vision). A video camera placed 25 m from the start, perpendicular to the swimming direction, recorded the performance of each swimmer during the clean swim phase. Variables measured included total race time, clean swimming speed (CSS), stroke rate (SR), stroke length (SL), and stroke index (SI = CSS x SL). Comparisons of performance were made between the classes and between men and women. RESULTS: The men showed no significant differences between S12 and S13 on any of the variables or between all three classes on SL and SI. The S11 swimmers demonstrated a significantly slower total race time and CSS in both events. In the women, an increase in class was associated with a decrease in total race time, faster CSS, and increase in SI. In comparing men and women, men demonstrated a significantly faster CSS and total race time during both events, whereas no differences were observed in SR. CONCLUSION: Stroke parameters during the clean swim phase were affected by visual impairment in both men and women. The male classes, however, were not clearly distinct from each other based on the swimming variables measured, as no significant differences were found between S12 and S13 in either event. With the exception of stroke rate and length, performance of the women tended to increase with an increase in class.

[The value of sports for handicapped patients. Achieving social integration--building bridges by paralympic sports]. / Die Bedeutung des Sports für Behinderte. Gesellschaftliche Integration verwirklichen--Brücken bauen durch den paralympischen Sport.

It is important to reflect back on the enormous changes that have taken place in society over the past century that have affected the quality of life of disabled persons and societal attitudes towards disability. Although great progress has been made, these people remain marginalized and disadvantaged, and despite all the efforts of volunteers, professionals, and governments, we cannot categorically state that they are fully socially integrated. The term disability continues to carry an enormous stigma, and therefore it is important to examine the concept of social integration and the issues around it as they affect disabled persons and the role of the International Paralympic Committee (IPC) movement in achieving this end.

The effects of surface anaesthesia on the autonomic dysreflexia response during functional electrical stimulation.

Recently, increases in blood pressure (BP) and concomitant bradycardia, suggestive of autonomic dysreflexia (AD), have been documented during functional electrical stimulation (FES) in individuals with a high spinal cord injury (SCI). If uncontrolled, this response could preclude the safe use of FES among such individuals. FES induced pain is partly related to stimulation of skin nociceptors. Therefore, measures to reduce skin sensitivity may reduce the risk of AD during FES. The purpose of this study was to determine if topical anaesthetic applied over the site of electrical stimulation could minimize the AD cardiovascular and hormonal responses to FES in individuals with SCI above the T6 level. Seven subjects with a SCI above T6 received FES to the quadriceps muscle of each leg under two conditions on two different testing days. The two treatment conditions, topical anaesthetic and placebo creams, were double blinded and randomized. The cream was administered to an area the size of the electrode (10 x 10 cm) 1 h prior to stimulation. Stimulation began at 0 mAmps and increased by 16 mAmps every 2 min until an intensity of 160 mAmps was achieved. HR and BP were measured at each stimulation intensity level. Catecholamines were analyzed three times during the stimulation protocol (pre, mid and post stimulation intensities). At the end of the stimulation protocol, FES induced isometric quadriceps contraction force at 160 mAmps intensity was measured using a hand held dynamometer. As FES stimulation intensity increased, significant rises in systolic and diastolic BP were seen, with a concomitant progressive drop in HR. The AD response to stimulation was not significantly different between the topical anaesthetic and placebo conditions. Serum catecholamine (epinephrine and norepinephrine) levels tended to rise with increasing FES intensity levels but did not reach statistical significance. The two treatment conditions did not significantly affect serum catecholamine levels or FES-induced quadriceps contraction force. In summary, FES application to the quadriceps muscle in high level SCI subjects resulted in significant increases in BP, decreases in HR (AD-like response), a trend towards elevations in catecholamine levels, and no difference in quadriceps muscular strength. However, these responses were unaffected by the use of topical anaesthetic cream on the skin at the stimulation site. This suggests that other mechanisms than skin nociception are operative in FES-induced AD.

Assessment of isokinetic and hand-held dynamometer measures of shoulder rotator strength among individuals with spinal cord injury.

OBJECTIVE: To determine the intrarater reliability of the hand-held dynamometer (HHD) for the measurement of shoulder rotation and to examine the relationship between the peak force values of the HHD and the isokinetic dynamometer. PARTICIPANTS: Twenty-five spinal cord injured individuals, 12 persons with paraplegia and 13 persons with tetraplegia between the ages of 18 and 42 years, were recruited from the community. SETTING: Private practice clinic. PROCEDURES: All participants were tested with the HHD by one examiner to determine reliability. On the same day, these participants underwent isokinetic testing to determine the relationship of the HHD and Cybex dynamometer measurements. RESULTS: The intraclass correlation coefficients for the intrarater reliability ranged from .89 to .96. The Pearson product moment correlation was used to analyze the relationship between the two devices. All coefficients (.52 to .88) were statistically significant (p < .01); however, separate analyses for the persons with paraplegia and tetraplegia differed considerably. There was substantial variability of the isokinetic strength values at the lower levels of isometric strength. CONCLUSIONS: The HHD can be used reliably to measure shoulder rotation in paraplegic and tetraplegic spinal cord injured individuals. Although it appears that the relationship between HHD and isokinetic measurement is poor for the participants with tetraplegia, the variability of the isokinetic scores indicates that this observation may be a function of the method of isokinetic measurements. Further study with a modified isokinetic testing protocol is needed to clarify the results of the participants with tetraplegia.

Hormonal responses to graded-resistance, FES-assisted strength training in spinal cord-injured.

Functional electrical stimulation (FES) assisted resistance training has been effective in increasing muscular strength and endurance in spinal cord injured men and women in preparation for FES-assisted cycle programs and for FES-assisted standing and walking. Increases in blood pressure and a concomitant bradycardia suggestive of autonomic dysreflexia have been reported during FES-assisted resistance training. Self-induced autonomic dysreflexia in athletes who use wheelchairs suppressed the normal exercise induced serum testosterone increase. We, therefore, examined the changes in hematocrit and circulating levels of testosterone, sex hormone binding globulin (SHBG), cortisol, prolactin, norepinephrine and epinephrine during FES assisted resistance exercise in five high spinal cord injured men (SCI) and comparable maximal exercise in five able bodied controls (AB). Mean serum testosterone levels significantly increased with FES-assisted resistance training in SCI and maximal resistance exercise in AB with no significant change in hematocrit or SHBG. Prolactin, cortisol and epinephrine levels were unchanged while norepinephrine levels were significantly increased in SCI and AB. These findings suggest that there is no concern over inadequate physiological androgen response to an exercise stimulus in SCI. The data do not support the previous findings that elevated levels of norepinephrine in autonomic dysreflexia suppress testosterone response to exercise.

Physiological correlates of simulated wheelchair racing in trained quadriplegics.

This study examined the physiological responses during a 7.5-km simulated wheelchair race (SR) performed on rollers by 8 male quadriplegic marathon racers and analyzed the factors associated with SR time. Cardiac output (Q) was estimated during the SR using carbon dioxide rebreathing, from which stroke volume (SV) and (alpha-v)O2 diff were calculated. Subjects raced at 90 and 93% of peak oxygen uptake (VO2) and peak heart rate, respectively. SR time was inversely related (p < 0.05) to peak VO2, and VO2, Q, and SV during the SR, but not (alpha-v)O2 diff, age, and lesion level. Multiple regression analysis included only absolute SR VO2 in the equation to predict SR time: Y = -29.7X + 65.9; SE = 5.8. SR VO2 was significantly (p < 0.05) related to Q and SV but not to (alpha-v)O2 diff. These descriptive data suggest that SR performance in trained male quadriplegics might be limited by central, as opposed to peripheral, factors that determine VO2.

Efficacy of rowing, backward wheeling and isolated scapular retractor exercise as remedial strength activities for wheelchair users: application of electromyography.

Shoulder dysfunction due to regular wheelchair use is a common problem among people with spinal cord injuries. As a remedial measure, strengthening of the scapular retractor muscles has been suggested. Electromyographical analysis was utilized to examine scapular retraction muscle use during rowing, backward wheeling and a standardized scapular retraction exercise in seven people with spinal cord injuries and seven able bodied subjects. In addition, a pilot study using indwelling electrodes was completed to validate the use and placement of surface electrodes. Both rowing and the standardized scapular retraction exercise recruited higher levels of retractor involvement than backward wheeling. We suggest that rowing, because of its value as a cardiovascular exercise and high level of retractor recruitment, is an appropriate and effective means of remediating scapular retractor weakness.

Reliability of the maximal aerobic power and ventilatory threshold in adults with cerebral palsy.

This study examines the test-retest reliability of the ventilatory threshold (VT) and the maximum oxygen uptake (VO2max) in adults with cerebral palsy (CP). Nine subjects completed two continuous incremental tests on either a wheelchair ergometer (WE, n = 5) or a cycle ergometer (CE, n = 4) to volitional fatigue. Metabolic and cardiorespiratory responses were continuously monitored during the tests with an automated metabolic cart interfaced with an electrocardiogram. Two experienced evaluators identified the VT using standardized respiratory gas exchange criteria. The reliability coefficient for the VO2max during the two trials was significant (r = 0.83, p < .05). However, there was no significant relationship (p > .05) between the two trials for the oxygen uptake (VO2) at the VT identified by the two evaluators (r = 0.45 and 0.43). The correlations for this variable between the two evaluators were highly significant on each trial (r = 0.99 and 1.00, p < .01). No significant differences were observed between the two trials for the VO2 at the VT and the VO2max. These results suggest that when monitoring the cardiorespiratory fitness of adults with CP, it may be more appropriate to evaluate the VO2max rather than the VT, because the former variable can be reliably determined in these individuals whereas the latter lacks consistency.

Testosterone, cortisol and catecholamine responses to exercise stress and autonomic dysreflexia in elite quadriplegic athletes.

Episodes of short high intensity exercise are associated with an increase in circulating total testosterone (T) in men. Mechanisms may include hemoconcentration, decreased metabolic clearance and/or increased synthesis. Beta-blockade abolishes the T response suggesting a direct beta-adrenergic effect on the testes. Some spinal cord injured (SCI) athletes deliberately induce autonomic dysreflexia (boosting) to enhance performance. Associated with this practice are elevated catecholamine (CA) levels and exaggerated responses to serum catecholamine levels. Since basal T levels are reported to be normal in the SCI male, the T response to acute high intensity exercise might be expected to be exaggerated by boosting and associated elevated CA levels. The acute exercise T response has not been examined in SCI men to date. To determine whether the increased CA values associated with boosting enhanced the exercise-induced T elevation we measured circulating levels of T, cortisol (C), norepinephrine (NE) and epinephrine (E) before and after maximal exertion and a simulated 7.5 km race with and without boosting in eight elite quadriplegic athletes. Maximal incremental exercise and a simulated 7.5 km race resulted in a rise in T similar to able bodied men under normal exercise conditions. Under boosted conditions the rise in T was eliminated while NE levels were significantly elevated above unboosted levels. The data may suggest an inhibitory role for CA on T production or release under conditions of extreme stress. Other possible mechanisms include C induced suppression, impaired gonadotropin stimulation of the Leydig cell and CA mediated alterations in gonadal blood supply.

Upper extremity peripheral nerve entrapments among wheelchair athletes: prevalence, location, and risk factors.

Wheelchair athletes commonly experience hand pain and numbness. This investigation studied the prevalence, location, and risk factors of upper extremity peripheral nerve entrapment among wheelchair athletes. Clinical and electrodiagnostic assessments were performed on both upper extremities of 28 wheelchair athletes and 30 able-bodied controls. Included in the assessment were short-segment stimulation techniques of the median nerve across the carpal tunnel and the ulnar nerve across the elbow. By clinical criteria, the prevalence of nerve entrapment among the wheelchair athletes was 23%, whereas it was 64% electrodiagnostically. The most common electrodiagnostic dysfunction was of the median nerve at the carpal tunnel (46%), and the portion of the nerve within the proximal carpal tunnel was most frequently affected. Ulnar neuropathy was the second most common entrapment electrodiagnostically (39%) and occurred at the wrist and forearm segments. Disability duration correlated significantly with electrophysiologic median nerve dysfunction.

Physiological responses during wheelchair racing in quadriplegics and paraplegics.

The purposes of this study were: (1) to compare the physiological responses during simulated wheelchair racing (SR) between male quadriplegics and paraplegics, (2) to test the validity of the SR against a track race (TR) and (3) to examine the relationship between the peak oxygen uptake (peak VO2) and wheeling velocity (WV) during the SR and TR. Seven quadriplegics (C5-8 lesions) and six paraplegics (T5-L4 lesions) completed (1) an incremental wheelchair velocity test, (2) a SR (1.6 km for quadriplegics and 3.2 km for paraplegics), and (3) an indoor TR of the same distance. The subjects performed the incremental velocity test and SR in their personal wheelchairs mounted on a roller system interfaced with customized software programmed to provide velocity and distance feedback. Physiological responses were monitored using an automated metabolic cart and electrocardiogram. Blood lactate concentration [La] was determined from finger prick samples. Peak VO2 and peak heart rate (peak HR) were significantly higher in the paraplegics compared to quadriplegics: 1.90 +/- 0.54 vs 1.07 +/- 0.35 l/min, and 188 +/- 11 beats/min vs 117 +/- 12 beats/min respectively. The paraplegics exercised at significantly (p < 0.05) higher percentages of peak VO2 and peak HR during the SR compared to quadriplegics (95% vs 76% and 95% vs 86%, respectively). No significant relationships (p < 0.05) were observed between the peak VO2 and WV during the SR and TR in either group.(ABSTRACT TRUNCATED AT 250 WORDS)

Evidence of autonomic dysreflexia during functional electrical stimulation in individuals with spinal cord injuries.

The purpose of the investigation was to examine the safety and efficacy of functional electrical stimulation (FES)-assisted hydraulic resistance training in improving cardiovascular fitness in persons with spinal cord injuries. The cardiopulmonary responses of 10 high spinal cord injured (SCI) and five able bodied (AB) subjects were assessed during three bouts of FES-assisted leg extension exercise. The protocol involved three 30-minute tests: (1) unloaded leg extension, (2) hydraulically-resisted leg extension (loaded), and (3) a reproduction of the unloaded and loaded protocols to measure cardiac output (Q). Pre-measurements were made of body mass, mean limb weight, maximal force output and maximal oxygen uptake (incremental arm ergometry). Oxygen uptake (VO2), minute ventilation (Ve), respiratory exchange ratio (RER), heart rate (HR), blood pressure (BP) were recorded before, during and after tests. There was a significant difference in VO2 max between SCI and AB subjects. Cardiac output significantly increased between the loaded and unloaded tests. The significant increases from rest to unloaded and loaded exercise pointed to the potential value of adding resistance to a leg extension training regime. Heart rate and BP of the participants with SCI consistently demonstrated a response suggestive of autonomic dysreflexia. Upon stimulation an immediate increase in (predominantly systolic) BP was observed, followed by a fall in HR. On cessation of stimulation HR exhibited a substantial rebound effect and BP returned to normal levels. This response was highly reproducible and suggests caution be exercised in the use of FES for people with SCI with lesion levels above the major splanchnic outflow (T6).

Electrical stimulation-assisted rowing exercise in spinal cord injured people. A pilot study.

Recently a FES (functional electrical stimulation)-assisted rowing machine was developed to enhance cardiovascular training in people with spinal cord injuries. The machine was assessed in terms of its efficacy as a training tool. Six patients who were quadriplegic (C6-T1) and 2 who were paraplegic (T3-6) completed a series of three tests in succession: (1) leg stimulation only (quadriceps and hamstring groups)--'Stim', (2) arm row only--'Row' and (3) simultaneous row and stimulation--'R & S'. Measurements recorded included oxygen uptake (VO2), minute ventilation (Ve), respiratory exchange ratio (RER), heart rate (HR) and blood pressure (BP). In addition, 6 out of the 8 subjects took part in a qualitative assessment comprising a guided interview exploring the subject's perception of the machine and test. Significant increases in VO2 were demonstrated between the three tests with R & S producing mean steady-state values of 16.34 nm (+/- 0.74) ml/kg/min (83% of maximum). These values represented a 12% increase over Row alone. Of interest was the qualitative assessment which revealed that subjects perceived R & S to be easier than Row despite the higher levels of VO2 observed. The results suggest that the rowing machine represents a potentially valuable hybrid training device that may significantly reduce risk factors for cardiovascular disease and improve the quality of life of people with SCI.

Anaerobic threshold in wheelchair athletes with cerebral palsy: validity and reliability.

This study examined the validity and reliability of the anaerobic threshold (AT) using blood lactate (ATLa) and respiratory gas exchange (ATg) criteria during cycle ergometry (CE) and wheelchair ergometry (WE) in athletes with spastic cerebral palsy (CP). Eleven subjects attempted a discontinuous incremental test protocol, two minutes work interspersed with one minute rest, twice each on the CE and WE. Only five out of the 11 subjects were able to complete the CE tests, whereas all the subjects were able to complete the WE test. Inadequate hip flexion due to muscle spasticity was the primary limiting factor during the CE tests. Although the maximal aerobic power using this protocol was reliable during WE (r = 0.89, p < .05), the validity and reliability of the AT identified by two independent evaluators using these two techniques was questionable. Evaluator 1 was able to identify ATLa and ATg in seven out of the 11 cases, whereas evaluator 2 was successful in five and seven cases, respectively. It is unclear from these results whether the poor validity and reliability of the AT was due to the discontinuous test protocol used, or whether it was due to inconsistencies in the rate of lactate diffusion from the muscle into the blood due to variations in muscle spasticity during the test.

Maximal aerobic power in cerebral palsied wheelchair athletes: validity and reliability.

This study examined the validity and reliability of maximal aerobic power (VO2max) during wheelchair ergometry (WE) in wheelchair athletes with cerebral palsy. Six class 3 and class 4 male athletes with cerebral palsy completed two graded exercise tests to volitional fatigue on a wheelchair ergometer mounted on frictionless rollers. Four athletes were also able to complete two tests of bicycle ergometry (BE). Although the reliability coefficients for the VO2max during the two exercise modes were high (.89 and .93 for the WE and BE tests, respectively), the validity coefficients for this variable (ie, the correlations between WE and BE) were poor (.31 and -.24 for trials 1 and 2, respectively). Examination of the individual data indicated that athletes who used wheelchairs as their primary mode of ambulation had higher VO2max values during WE; whereas, those who used canes or no aids for daily ambulation had higher values on BE. Because of the specificity of the, VO2max response, it is recommended that the primary mode of ambulation be considered when deciding on the testing mode for evaluating the cardiorespiratory fitness of athletes with cerebral palsy.

Reliability of peak physiological responses during wheelchair ergometry in persons with spinal cord injury.

This study examined the test-retest reliability of peak physiological responses during wheelchair ergometry (WE) in individuals with spinal cord injury (SCI). Seven wheelchair dependent subjects, two with paraplegia (T10-11 and T11-12 lesions) and five with quadriplegia (all with C6-7 lesions), were given two incremental exercise tests to volitional fatigue on separate occasions within a one-week period. Each subject wheeled his or her personal wheelchair, which was mounted on a set of frictionless rollers with side-mounted flywheels. Metabolic and cardiorespiratory responses were continuously monitored by means of an automated metabolic measurement cart interfaced with an electrocardiograph. Statistical analysis revealed no significant differences (p greater than .05) between the mean values of the two test trials for six peak values. Reliability coefficients (p less than .01) were: oxygen uptake (0.98), heart rate (0.97), ventilation volume (0.96), respiratory exchange ratio (0.91), oxygen pulse (0.96), and ventilatory equivalent for oxygen (0.88). The investigators concluded that these six physiological responses in subjects with SCI undergoing WE are highly reliable, and that these variables can be used in the objective prescription, monitoring, and evaluation of exercise rehabilitation programs for individuals with SCI.

Effect of seat position on maximal linear velocity in wheelchair sprinting.

The purpose of this study was to investigate the relationship between seat position and linear velocity in wheelchair sprinting. Nine male subjects with various physical disabilities participated in the experiment. Linear velocity was determined by analyzing the filmed performance of subjects wheeling at maximum speed on a wheelchair ergometer. The results revealed no significant differences between the maximal linear velocities at each of the nine seat positions chosen for investigation. These findings suggest that given a limited variability in seat positions, maximal linear velocity will be minimally affected. Simple correlation procedures revealed a significant negative correlation between the length of push and linear velocity. This is in opposition to current findings and suggests that pushing frequency may be more critical than the length of push in generating maximum speed in wheelchair sprinting.

Physiological profiles of the Canadian Olympic Hockey Team (1980).

In order to establish baseline data and to prescribe training programmes to off-set weaknesses, selected measures of aerobic fitness (VO2max), muscular power (peak torque and watt output) and performance times on-ice were collected on the Canadian Olympic Hockey Team (1980). VO2max values (54 ml. kg. min) were similar to other non-endurance athletes. Peak torque values relative to body weight in knee extension at 30 degrees and 180 degrees . s-1 (3.62 an 1.85 Nm . kg-1) were the same at low speed but lower at high speed than other selected power athletes. The on-ice performance times showed higher speed of over 180' than professional and junior level players but the speed drop-off over six repeats was greater. There were no differences between positions on these measures. These data offer a baseline from which to compare other hockey players and suggest that the aerobic fitness levels and torque outputs at high speed are not well developed.

lsokinetic Torque Outputs of Professional and Elite Amateur Ice Hockey Players.

Instrumentation advances have recently allowed the isokinetic evaluation of muscle function for purposes of injury diagnosis, rehabilitation, and training prescription. This type of evaluation has been particularly useful for athletes in preparing for performance or returning to training following injury. lsokinetic testing of specific muscle groups and at the approximate limb speeds required for performance of the sport has allowed more specific analysis of the functional strengths and weaknesses of athletes. Isokinetic testing allows comparison of agonist and antagonist muscle groups for balance across a joint, for right and left side muscle group comparison, and for joint angle at peak torque. Several athletic groups have already been characterized; alpine skiing, track and field (sprinting, jumping, and walking), and orienteering. The purpose of this study was to evaluate the function of important muscle groups for the performance of ice hockey. The data provided the basis for devising a training program for the athletes and also provided data for the characterization of professional (NHL) and elite amateur (Olympic) ice hockey players. Analysis also provided comparative information about the two groups.J Orthop Sports Phys Ther 1981;3(2):42-47.